The invention relates to anaesthesia machines and more particularly to interlock devices for anaesthesia machine vaporizers and locking devices for connecting tubing to an anaesthesia machine.
Anaesthesia equipment typically consists of a trolley on which are mounted cylinders containing medical gases such as oxygen, air and nitrous-oxide and associated pressure regulating valves. Anaesthetic agents such as halothane and isoflurane are commonly administered by passing a carrier gas such as air or oxygen mixed with nitrous-oxide through a vaporizer which contains the liquid anaesthetic agent.
Conventional anaesthesia apparatus or machines commonly incorporate two or more separate vaporizers. Each vaporizer is arranged to dispense a metered amount of anaesthesia vapor into the patient breathing circuit or fresh gas line. These vaporizers may contain different anaesthetic agents so that the same equipment can be used for a series of surgical operations to supply the particular anaesthetic agent desired. The arrangement of more than one vaporizer on the same anaesthetic equipment does, however, lead to the possible risk that more than one vaporizer could accidentally be connected to the gas administration circuit at the same time. In order to cope with this problem, various interlock systems have been proposed in order to prevent more than one vaporizer being operated at the same time. For example, U.K. patent specifications Nos. 2052271 and 2193642 describe one such interlock system. While the interlock arrangements described in these two patent specifications are satisfactory with the type of hook-on vaporizers described in U.K. patent specification No. 1385670, there is at least one other widely used system in use for connecting vaporizer units to a gas administration circuit. There is, therefore, a need for a vaporizer interlock system which can be adapted for use with more than one type of gas administration system.
While the construction of commercially available vaporizers varies from manufacturer to manufacturer, the most common type of vaporizer comprises a canister including a reservoir for the anaesthesic agent, valve means and a rotatable dial coupled to the valve means for adjusting the valve means to establish the vaporizer concentration levels. Such machines may include a rotary dial for adjusting the opening of a valve in the vaporizer to divide the gas flow in the vaporizer in accordance with the dial setting. Part of the gas flow passes through a by-pass, without entering the vaporizer chamber (where the anaesthetic agent is located), while the remaining portion of the gas flow passes through the vaporizer chamber for saturation by anaesthesia vapor. The gas flow which is saturated with the vapor is then combined with the by-pass gas flow so that the gas leaves the vaporizer carrying a set concentration of anaesthesia. The introduction of the gas carrying anaesthesia vapor into the fresh gas line is effected by an outlet valve under the control of a separate lock/unlock switch. A pair of rotary cams and a pivoting lever are provided to serve as an interlock to insure that the outlet of the vaporizer is opened when the rotary dial is adjusted to any particular setting and to prevent the adjustment dial from being rotated to any setting when the lock/unlock switch is closed, thereby precluding any gas from passing into the vaporization chamber when the outlet of the vaporizer is closed.
Many such interlock systems provide an interlock only between two vaporizers of one connector type.
It is an object of this invention to provide an improved interlock system which can be used with two or more vaporizers with the added feature that each of the vaporizers may be a different connector type.
The present invention also relates to a safety lock hose connector for use with the anaesthetic apparatus of the invention. Typical hose connectors for anaesthetic breathing systems, for example, comprise a tapered, hollow male member for insertion into a correspondingly internally tapered female member. The size and degree of taper of such connectors are covered by various national and international standards.
Commonly the male member is made of metal (generally stainless steel) and the female member is made of metal or of plastic material or, as described in GB-A-No. 1396096, may comprise a metal sleeve housed within a plastic housing.
One problem which can occur with such connectors is accidental disconnection and, clearly as can be appreciated, this can give rise to potentially severe problems. It is an object of the present invention to provide a hose connector having a securing system serving to prevent accidental disconnection but allowing for simple and rapid intentional connection and disconnection.
Accordingly, the invention comprises an interlock system for use with a plurality of vaporizers which, on activation of one of the vaporizers, prevents activation of any number of vaporizers to the right or the left of the activated vaporizer.
The invention also provides a hose connector comprising an externally tapered male connection member and an internally tapered, generally tubular, female connection member in which the male member is provided with a collar which defines, together with the male member, an annular recess for reception of the end of the female member, and the inner wall of the collar defining the recess has at least one helical groove extending from the free end of the collar towards the fixed end thereof: and the female member is provided with one or more external lugs or pins for engaging with the groove in the collar.
The invention also provides hose to hose connections on an anaesthetic apparatus in which hose is connected to the apparatus by means of the connector of the invention.